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Individuals without the mutation will be less likely to procreate. Those with the gene will then pass it on to a higher percentage of offspring than those without. Eventually, the mutation spreads throughout the population.

All that means is that failed mutations do not succeed. This does not make it more likely that a beneficial mutation occurs in the first place.

Mutations occur thousands, if not millions, of times each generation; of all those mutations, some will be detrimental, most will be neutral, and a precious few will be advantageous. Even that precious few statistically might be quite large numerically, however, depending upon the size of the population.

All that means is that failed mutations do not succeed. This does not make it more likely that a beneficial mutation occurs in the first place.

But it takes more than just a single mutation to produce a different species. And it usually takes more than a single mutation to make a major improvement to an existing biochemical pathway or to create a new or highly modified structure.

Natural selection acts as a ratchet for evolution: The first mutation spreads to a significant portion of the population, so that when a child is born with the right second mutation, chances are they also have the 1st mutation. Both mutations didn't have to pop up at the same time. This greatly magnifies the odds in favor of progress.